The invention relates to a control apparatus for a liquid medium, the apparatus comprising a body portion provided with flow channels, and the body portion comprising an inlet for the medium, an outlet for the medium to an apparatus that the medium is conducted to, a return point for the medium returning from the apparatus, and a discharge point through which the medium is discharged from the control apparatus; a flow control valve and means for measuring the flow and pressure being arranged after the medium inlet in essentially the flow direction of the medium in the flow channels of the body portion, and a pressure control valve for controlling the pressure in the flow channels between the flow control valve and the pressure control valve being arranged after the return point.
The above apparatuses are well known from different fields of technology. Examples for known solutions include the apparatuses of Finnish Patents 61,759, 61,760 and 89,747. These known apparatuses function flawlessly in most situations. In practice, however, it has become apparent that in certain cases of damage, they leave something to be desired. An example for such an instance is that the apparatus in which a liquid medium is used, e.g. a seal of the apparatus, is damaged so that pressurized medium flows into the control apparatus. The pressure will thereby rise excessively in the control apparatus, and the control apparatus may be damaged. At worst, damage in the control apparatus may even cause injury. Another drawback of known apparatuses is that in practice it is not always possible to see it clearly from the flow measuring means whether the medium is flowing or not, or whether e.g. a malfunction has occurred. Yet another problem is how to provide quick and practical flow connections for the medium.